The following U.S. patents are incorporated herein by reference in entirety.
U.S. Pat. No. 3,191,959 discloses a hand cart having a generally rectangular main frame, a pair of side structures hingedly connected to parallel side portions of the frame for independent swinging movement relative to the frame, and a bottom structure hingedly connected to a horizontal lower portion of the frame for independent swinging movement. The side and bottom structures together with the frames serve to define a vertically extending carrying space that is open at its front, when the side and bottom structures extend in planes at right angles to the general plane of the frame, wheel means mounted on the lower end of the cart, and means for detachably securing the lower edges of the side structures to the bottom structure. The securing means is detached by swinging the side structures in directions away from the bottom structure and about the axes of the pivotal connections between the side structures and the main frame. The side and bottom structures when the security means is disengaged are collapsible upon each other adjacent the front side of the frame.
U.S. Pat. No. 3,840,242 discloses a nestable transport rack having frame means which is composed of a nestable wheel supported base frame and a pair of horizontally spaced, upstanding and parallel side frame members rigidly secured to the base frame and extending upwardly therefrom. Shelf means are pivotally secured to the frame means and are pivotable between a generally horizontal position and a vertical position, the vertical position being parallel with the upstanding side frame members. Sidewall means are provided which are pivotally secured to each of the side frame members and are pivotable between a first position on opposite lateral sides of the shelf means when the shelf means are in the horizontal position, and a second position parallel to the shelf means when the shelf means is in the horizontal position. At least a portion of the nestable, wheel-supported base frame extends frontwardly of the upstanding side frame members and the shelf means when the shelf means is in the vertical position and the sidewall means is in the second position parallel to the shelf means and is capable of nesting with another of the transport racks.
U.S. Pat. No. 4,346,906 discloses a roll pallet comprising a frame, an end wall and a deck. Also, there may be two sidewalls pivotally connected to the end wall. The deck can be pivoted into a raised position in which it is parallel to the end wall, and the sidewalls can be folded inwardly. The pallet can then be nested, for storage, with another similar pallet, by virtue of the shape of the frame, which comprises two converging limbs. The frame is provided with wheels and the deck is provided with stabilizing wheels which resist toppling of the pallet when it is carrying a load.
U.S. Pat. No. 5,873,204 discloses a wheeled cart having a base and three sidewalls extending therearound and upward therefrom. A pair of partial doors is hingedly secured to and extends along edges of two opposing sidewalls for permitting partial coverage of a fourth side of the cart. Each partial door includes a spring-biased manually operable pin for cooperating with a plurality of slots in the cart base. The base front edge also has an inwardly angled portion along the length thereof that angles up to a horizontal shoulder. The horizontal shoulder includes the first pair of the plurality of pin retaining slots. A vertical portion then rises from the level of the shoulder to the level of the main area of the cart base. In this mode, the end of the pin rides up on the angled portion when the door is closed with sufficient force, thereby overcoming the biasing force of the spring. The pins of each door will then insert into the first slots in the shoulder area. The vertical edge prevents any further movement of the doors inward as the pins thereof are blocked thereby.